Calcium, the most abundant mineral in the body, is a major constituent of bone and teeth. This mineral also plays an important role in several physiological systems. Calcium is important for healthy bone and tooth development in the young and an adequate intake is essential. Calcium status may also be a factor in the development of osteoporosis in elderly people.
Since the body does not produce minerals, it is totally dependent on an external supply of calcium which is nutritional or supplementary. The importance of adequate calcium intake is recognized during the whole life of the human being. In 1994, the NIH Consensus Development Panel revised recommended daily allowances for calcium intake for each age group from 800-1200 mg per day to 1500 mg per day.
It has been found that organic acids salts of calcium are more bioavailable in general than the inorganic salts. Calcium citrate has advantages over other calcium salts for use in fortified foods because of its high bio-availability. Calcium citrate, as opposed to calcium in general, has only a marginal effect of interfering with the absorption of other minerals, especially iron. Also, long-term calcium supplementation with calcium lactate-citrate can reduce the risk of the formation of kidney and urinary stones since citrate ions are inhibitors of crystallization of stone-forming calcium salts.
Magnesium also plays an important role in the human organism. The adult body contains 20-28 g of magnesium, approximately 60% of which is present in the skeleton, 40% resides in the muscles and soft tissues and about 1% in the fluid. Magnesium participates in numbers of biochemical and physiological processes such as biosynthesis, glycolysis, transmission of the genetic code, enzyme activation, etc. Further, extracellular magnesium is critical to the maintenance of electrical potential of nerve and muscle membranes and for transmission of impulses across neuromuscular junctions. The RDA for adults of both sexes is accepted to be 4.5 mg/kg, or 280 mg for women and 350 mg per day for men aged 19 and above (Recommended Dietary Allowances, National Academy Press, Washington, D.C., 1989, 10th Edition).
The addition of calcium to water or clear beverages presents very significant problems. Firstly, if highly soluble sources of calcium (calcium chloride, etc.) are used, a high level of soluble calcium leads to undesirable flavor and destabilization of proteins. Secondly, slightly soluble sources of calcium will not cause destabilisation of protein micelles but they will precipitate out of the solution rapidly. Accordingly, the solubility of calcium sources has to be balanced within a very small range of solubility to avoid such problems.
Therefore, it would be highly desirable to have calcium and calcium-magnesium sources to fortify water, juices, beverages and other liquid food products without coagulation and sedimentation, with improved palatability, and without bitterness or off-flavors.
J09175994 discloses an liquid calcium drink prepared by dissolving a calcium source, calcium carbonate or pulverized shell of oyster with malic and/or citric and lactic acid, particularly at ratios 1:1-20, followed by heating at 50-100.degree. C. The advantage is to supply calcium with improved taste.
DE4111040 describes fruit juice enriched with a mixture tri-potassium citrate, calcium lactate, magnesium gluconate and ferrous gluconate. The pH of the fruit juice is preferably adjusted to 4.3 with lemon or lime juices. The advantage is supply minerals which may be insufficient in the diet, in a drink, in a form with a pleasant taste.
J55088685 describes a health drink composition containing calcium lactate, amino acid-rich vinegar, and optionally lactic acid, citric acid and/or apple vinegar in aqueous alkaline solution. The composition includes 500-1000 mg of calcium lactate and 500-3000 mg of amino acid-rich vinegar in 100 ml of solution and has a pH of 3.6-3.8 and a sugar content 6.5-10%. Optionally, 150-500 mg of lactic acid, 150-500 mg of citric acid and/or 500-2000 mg of apple vinegar are also combined in 100 ml of solution. Citric acid, honey, perfume, etc. are optionally included and combined. By using calcium lactate and amino acid-rich vinegar, the drink contains 1200 ppm of calcium. It is stated that calcium ions are easily absorbed and the drink prevents blood acidification and various diseases and disorders caused by calcium deficiencies.
Calcium and vitamin C containing beverages with improved color stability are described in U.S. Pat. No. 5,424,082. Stable nutritional vitamin and mineral supplemented beverages are described in U.S. Pat. No. 4,992,282.
A majority of these patents do not address the issue of the quantities of these drinks that must be consumed in order for one to obtain the daily recommended allowances of calcium and other nutrients from such preparations. Such nutritional drinks also lack organoleptic properties for good consumer acceptance. Accepted calcium salts such as calcium carbonate, calcium phosphate and calcium citrate for biological use tend to have very poor water solubility resulting in precipitation. Most soluble calcium salts have a very unpleasant bitter taste, while others (e.g., calcium glycero-phosphate) are very expensive or, such as calcium lactate, have very low calcium content.
Thus, there is a need for good tasting bottled water, juices and beverages or other liquid foods that contain a sufficient amount of calcium to meet the US Daily Recommended Allowances.